Electro-osmosis of viscoelastic fluids and prediction of electro-elastic flow instabilities in a cross slot using a finite-volume method

Afonso, A.M.; Pinho, F.T.; Alves, M.A.

doi:10.1016/j.jnnfm.2012.05.004

Cited by 38 publications

(36 citation statements)

References 45 publications

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“…Sousa et al 21 extended the analysis of Afonso et al 18,19 by considering the formation of a skimming layer without polymer additives near the walls, and Dhinakaran et al 22 analyzed the channel flow for the full PTT model with non-zero second normal-stress difference by considering the full Gordon-Schowalter convected derivative but restricting the analysis to pure electro-osmosis flow (without a pressure gradient). Recently, Afonso et al 23 presented analytical solutions for fully developed EOF by considering polymer solutions described by the sPTT and FENE-P 24 models with a Newtonian solvent. Hayat et al 25 presented an exact solution for the electro-osmotic flow of a generalized Burgers fluid and more recently Afonso et al 26 also solved analytically the channel flow of stratified immiscible fluids driven by electro-osmosis assuming a planar interface between the two viscoelastic immiscible fluids, an arrangement usually employed for fluid pumping using electrokinetic effects.…”

Section: -3mentioning

confidence: 99%

Electro-osmotic and pressure-driven flow of viscoelastic fluids in microchannels: Analytical and semi-analytical solutions

et al. 2016

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In this work, we present a series of solutions for combined electro-osmotic and pressure-driven flows of viscoelastic fluids in microchannels. The solutions are semi-analytical, a feature made possible by the use of the Debye–Hückel approximation for the electrokinetic fields, thus restricted to cases with small electric double-layers, in which the distance between the microfluidic device walls is at least one order of magnitude larger than the electric double-layer thickness. To describe the complex fluid rheology, several viscoelastic differential constitutive models were used, namely, the simplified Phan-Thien–Tanner model with linear, quadratic or exponential kernel for the stress coefficient function, the Johnson-Segalman model, and the Giesekus model. The results obtained illustrate the effects of the Weissenberg number, the Johnson-Segalman slip parameter, the Giesekus mobility parameter, and the relative strengths of the electro-osmotic and pressure gradient-driven forcings on the dynamics of these viscoelastic flows.

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Section: -3mentioning

confidence: 99%

Electro-osmotic and pressure-driven flow of viscoelastic fluids in microchannels: Analytical and semi-analytical solutions

et al. 2016

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“…As reviewed recently by Zhao and Yang , there have been several dozens of theoretical (and numerical) papers on electroosmotic flow and particle electrophoresis in non‐Newtonian fluids. Various constitutive equations have been used to simulate the fluid rheological properties. In contrast, experimental studies in this direction have been significantly lacking.…”

Section: Introductionmentioning

confidence: 99%

Electroosmotic flow of non‐Newtonian fluids in a constriction microchannel

Malekanfard

et al. 2018

Electrophoresis

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Insulator‐based dielectrophoresis has to date been almost entirely restricted to Newtonian fluids despite the fact that many of the chemical and biological fluids exhibit non‐Newtonian characteristics. We present herein an experimental study of the fluid rheological effects on the electroosmotic flow of four types of polymer solutions, i.e., 2000 ppm xanthan gum (XG), 5% polyvinylpyrrolidone (PVP), 3000 ppm polyethylene oxide (PEO), and 200 ppm polyacrylamide (PAA) solutions, through a constriction microchannel under DC electric fields of up to 400 V/cm. We find using particle streakline imaging that the fluid elasticity does not change significantly the electroosmotic flow pattern of weakly shear‐thinning PVP and PEO solutions from that of a Newtonian solution. In contrast, the fluid shear‐thinning causes multiple pairs of flow circulations in the weakly elastic XG solution, leading to a central jet with a significantly enhanced speed from before to after the channel constriction. These flow vortices are, however, suppressed in the strongly viscoelastic and shear‐thinning PAA solution.

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“…The shear‐thinning effect of the prepared solutions is characterized by the power‐law index, n , in Table , where a smaller value indicates a greater shear thinning effect (note a fluid with

n < 0.65

can be viewed as a strongly shear thinning fluid ). The elasticity effect of the prepared fluids is often characterized by the Weissenberg number ,

W i = \frac{2 λ V}{w}

where λ is the fluid relaxation time, V is the average electroosmotic velocity in the main‐branch of the microchannel, and w is the width of the main‐branch. A larger value of

W i

indicates a stronger elasticity effect, which may be a result of either an extended relaxation time or an increased fluid velocity.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, Afonso et al. numerically simulated the elastic instability in the EOF of Upper‐Convected Maxwell fluids through a planar cross‐slot device. Their 2D model predicted a direct flow transition from a stable symmetric state to a time‐dependent asymmetric state without crossing the steady asymmetric state.…”

Section: Introductionmentioning

confidence: 99%

Elastic instabilities in the electroosmotic flow of non‐Newtonian fluids through T‐shaped microchannels

Song

et al. 2019

Electrophoresis

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Elastic instabilities in the electroosmotic flow of non-Newtonian fluids through T-shaped microchannelsElectroosmotic flow (EOF) has been widely used to transport fluids and samples in microand nanofluidic channels for lab-on-a-chip applications. This essentially surface-driven plug-like flow is, however, sensitive to both the fluid and wall properties, of which any inhomogeneity may draw disturbances to the flow and even instabilities. Existing studies on EOF instabilities have been focused primarily upon Newtonian fluids though many of the chemical and biological solutions are actually non-Newtonian. We carry out a systematic experimental investigation of the fluid rheological effects on the elastic instability in the EOF of phosphate buffer-based polymer solutions through T-shaped microchannels. We find that electro-elastic instabilities can be induced in shear thinning polyacrylamide (PAA) and xanthan gum (XG) solutions if the applied direct current voltage is above a threshold value. However, no instabilities are observed in Newtonian or weakly shear thinning viscoelastic fluids including polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), and hyaluronic acid (HA) solutions. We also perform a quantitative analysis of the wave parameters for the observed elasto-elastic instabilities.

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Electro-osmosis of viscoelastic fluids and prediction of electro-elastic flow instabilities in a cross slot using a finite-volume method

Cited by 38 publications

References 45 publications

Electro-osmotic and pressure-driven flow of viscoelastic fluids in microchannels: Analytical and semi-analytical solutions

Electro-osmotic and pressure-driven flow of viscoelastic fluids in microchannels: Analytical and semi-analytical solutions

Electroosmotic flow of non‐Newtonian fluids in a constriction microchannel

Elastic instabilities in the electroosmotic flow of non‐Newtonian fluids through T‐shaped microchannels

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